Feed mechanisms for sewing machines



June 21, 1938, G. SAUER FEED MECHANISMS FQR sEwiNe MACHINES 2 Sheets-Sheet 1 Filed Dec. 1'7. 1935 I N VEN TOR: @50195 5mm;

June 21, 1938. fsAuER FEED MECHANISMS FOR sswme MACHINES 2 sheets-sheet 2 Filed Dec. 1'7, 1935 IN VEN TOR: .gaorga Sam/z;

WW I Patented June 21, 1938 UNITED STATES PATENT FEED MECHANISMS FOR SEWING MACHINES poration of Illinois Application December 17, 1935, Serial No. 54,805

8 Claims.

This invention relates to feed mechanisms for sewing machines, particularly sewing machines of the rotary hook lock stitch type. More especially. my invention is concerned with fourmotion feed mechanisms, wherein a feed element is lifted and so held while on its active or fabric advancing stroke, and lowered away from the fabric on its idle or return strokes.

My invention is directed toward the provision of a simple and reliable feed mechanism operative upon the above principle, which is simple in construction, positive and reliable in operation, capable of adjustment to vary the stroke of the feed element, and, moreover balanced in its movements so that the machine with which'it is associated can be operated at high speeds with a minimum of noise and vibration.

Another object of my invention is to provide a feed mechanism having the above mentioned characteristics, wherein, for the sake of .compactmess, the feed and lift inducing elements are all disposed in the same vertical plane; and wherein the feed bar extends rearwardly fro-m actuating means disposed at the front of the machine so that auxiliary feeding devices such as puller rollers can be located in closer proximity to the stitching instrumentalities than possible with feed mechanisms of the usual construction and arrangement.

Other objects and attendant advantages will appear from the following detailed description of the attached drawings, wherein, Fig. I is a View partly in front elevation and partly in longitudinal section, of a lock stitch sewing machine conveniently embodying my improved feed mechanism.

Fig. II is a bottom plan view of the machine.

Fig. III is a fragmentary detail view in elevation on a larger scale, looking as indicated by the arrows IIII1I in Fig. I; and

Fig. IV is a fragmentary sectional view, likewise on a larger scale, taken as indicated by the arrows IV-IV in Figs. I and II.

The sewing machine herein illustrated for the purpose of exemplifying my invention is a vertical hook lock stitch machine of the type featured in a co-pending patent application, Serial No. 53,552 filed on December 9, 1935 in the names of Norman V. Christensen and Oscar Quist. As

shown, the work support I of the machine is overhung by a hollow horizontal arm 2 extending forwardly from an integral hollow standard 3 at the rear end of said work support. Journaled withinthe hollow of the arm 2 is a main shaft 4 75 of the machine, said shaft being provided with a combined hand and belt wheel 5 so that the machine can be operated either manually or by power. Through suitable connections (not illustrated) the main shaft l transmits up and down movement to a needle bar 6 having guidance in 5 a head I at the forward end of the arm 2 and carrying a needle 8 at its lower end. Also guided in the head I, is a presser bar 9 which is urged downward by a spring (not shown) so that it can yield as fabric is passed beneath a presser foot IE1 at the bottom end of said bar. Longitudinally of the machine below the work support I is a rotary shaft H, which, at an intermediate point, is journaled in a bearing lug I2 pendant from said work support. At the right hand end of the machine, the shaft ll extends through a bearing bushing l3 into a lubricant housing M in direct communication with the hollow of the standard 3. Through a train of gear wheels l5, l5 and i1 within the hollow standard 3 and the 1 lubricant housing M, unison rotary motion is imparted to the rotary shaft I! from the main shaft :3. Cooperating with the needle 8 below the work support I, is a rotary hook l8, see Fig. III, whereof the shaft (not shown) has bearing in a 5 journal member l9 through which the shaft ll extends and within the hollow of which the rotary hook shaft is interconnected by bevel gear wheels (not shown) with said shaft. The journal member Hi can he slid along the shaft II for 30 adjustment of the rotary hook l8 laterally relative to the needle 8, and is securable in adjusted positions by means of a screw 28 which passes through a horizontal slot 2| in a pendant flange 22 of the work support I At its outer end, the 35 shaft H has journal support in a bearing bracket 23 which is secured to the flange 22 with capacity for adjustment along said shaft by a screw 25 passing through another horizontal slot 26 in said flange. 40

Having now described the sewing machine suficiently to enable understanding of my invention, I will proceed to the feed mechanism, which more especially constitutes the subject of the present application. As shown, this mecha- 45 nism comprises a feed dog 21 having toothed surfaces to operate within suitable apertures in the throat plate 28 of the machine, said feed dog being secured, with capacity for vertical adjustment, to a feed bar 29 by means of a screw 30. 50 From Fig. III, it will be observed that the feed bar 29 is formed with a portion 3| which extends inwardly from the front of the machine over the shaft II and with a downwardly and outwardlyextending curved arm 32 which under-reaches said shaft and which is pivotally connected by a pin 33 to the pendant clevised suspension arm 34 of the strap 35 associated with an eccentric 36 on the shaft H in the same vertical plane with the feed bar. As shown, the eccentric 36 is secured to the shaft l l in the interval between the journal member IQ for the rotary hook l8 and the end bearing bracket 23. As further shown in Fig. III, the over-reaching portion 3| of the feed bar 29 has its outer end pivotally connected to a pin 3? at the top end of a bifurcated rocker 38 which also lies in the same plane with said feed bar and which is secured by cotter pins 39 to a rock shaft 40. This rock shaft 40 extends parallel with the rotary shaft III below the work support l and is journaled in spaced pendant bearings M and 42 of said work support, said rock shaft being held against axial displacement by collars 13 thereon which respectively engage the bearing 42 at opposite sides. Secured to the shaft ll adjacent the bearing lug I2 is an eccentric M whereof the strap 45 has a vertical arm &6 which, through a pivot pin 41, is coupled with the swinging end of a horizontal lazy bar 48 which is fulcrumed on a pin 49 secured by set screws 50 in another pendant lug 5| of the work support, see Fig. IV. Also coupled at one end with the pin 51 is a horizontal link 52 which, at its opposite end, has pivotal connection with a pin 53 adjustable along an arcuate slot 54 of an actuating arm 55 clamped to the rock shaft 49.

The operation of the feed mechanism is as follows: As the shaft ll rotates, the eccentric M will move the eccentric strap up and down incident to which the pivot pin 41 will be confined by the lazy bar 58 to swing in an are about the fulcrum axis d9 of said bar with resultant impartation of endwise movements to the link 52. Through the actuating arm 55, the oscillating shaft 40 and the rocker 38, such movements of the link 52 will be translated into horizontal movements of the feed bar 29 with the suspended pivotal connection 33 of the latter swinging about the eccentric 35. The movement imparted by the eccentric M to the link 52 is fixed, but by shifting the pivot connection of said link up or down along the curved slot 54 of the actuating arm 55 it is evident that the stroke of the feed bar can be increased or decreased as may be desired or required. In the present instance the curvature of the slot 54 in the arm 55 is substantially concentric with the axis of the pin 41. By selecting centers of curvature such for example as at a or b in Fig. IV above or below the axis of the pin 47!, it is possible to determine curvatures A or B for the slot 54 of the arm 55 such that by shifting of the connection 53, the stroke of the feed dog 21 can be increased or decreased at either end thereof. In order to substantiate the statement just made, let it be assumed that the points a and b be the upper and lower limits of movement of the axis M under the influence of the eccentric M. Then if the curvature of the arm 55 be A struck from the center a it will be apparent that the active or feed movement of the feed dog 2'! will always terminate at the same point irrespective of the position of the center 35 on said arm. On the other hand if the curvature of the arm 55 be B struck from the center b, the feed movement of the feed dog 21 will always commence at the same point regardless of the shifting of the center 35 along the arm. The foregoing examples are to be considered as indicative of other simple or compound curvatures which may be given to the slot 54 of the actuating arm 55, depending upon the changes desired in the feed movements of the feed dog. In performing its rise and fall movements under the action of the eccentric 36, it will be observed that the feed bar 29 will pivot on the pin 3'! by which the overreaching portion 3| of said bar is connected to the swinging end of the rocker 38. By virtue of the translation of the vertical movements of the eccentric 44 into easy horizontal movements of the link 52 through the lazy bar 48, and since the feed bar is fioatingly supported in the manner illustrated with freedom of movement on the pivot centers '33 and 31, the action of the feed mechanism as a whole is well balanced and smooth and favors operation of the sewing machine at high speeds with a minimum of noise and vibration. The described construction of the feed bar 3| and disposal of the feed stroke means and its adjusting means at the front of the machine is not only advantageous in that it renders these parts readily accessible for inspection and oiling when the machine is swung up on the usual mounting hinges on a work table, but in that it leaves a clear commodation of auxiliary feed means such as puller rollers in close proximity to the needle 3 and the cooperating rotary hook 98. It will be further noted that since the rocker 38 and the eccentric strap 35 lie in the same vertical plane with the feed bar 3i, these parts are in perfect balance which renders their operation smooth and vlbrationless at high speeds. This arrangement also favors lateral compactness and allows positioning of rotary hooks in closer proximity to the stitch line when two hooks are used.

The use of my improved feed mechanism is not confined of course to single needle vertical hook lock stitch sewing machines, since by suitable modifications within the scope of the appended claims, it can be adapted to multi-needle sewing machines as instanced in the co-pending application to which attention has been directed, as well as to other types of sewing machines, with attainment of advantages equal in all respects to those hereinbefore pointed out.

Having thus described my invention, I claim:

1. Feed mechanism for sewing machines comprising a shaft; an eccentric on said shaft; a feed bar pivotally supported in suspension by a strap in the same plane therewith for reception of rise and fall movements from said eccentric, said bar having a portion extending over the shaft and terminating at the front of the machine; and means coordinated with the end of the over-reaching portion of the feed bar for imparting feed movements to said bar.

2. Feed mechanism for sewing machines comprising a rotary shaft; a feed bar with a portion extending over said rotary shaft and a portion extending beneath said rotary shaft; pivotal suspension and actuating means on the rotary shaft coordinated with the under-reaching portion of the feed bar to impart rise and fall movements to said bar; and means for imparting feed movements to the feed bar including a rocker, an oscillating shaft for said rocker, an actuating arm on the oscillating shaft, an eccentric on the rotary shaft, an associated strap with a vertical arm, a horizontal lazy bar fulcrumed to swing on a fixed center and having pivotal connection at its free end with the vertical arm of the eccentric strap, and a horizontal link connecting the actuating arm with the pivot connection aforesaid.

space at the rear for acforwardly toward the front of the machine over a 3. Feed mechanism for sewing machines comprising a rotary shaft; a feed bar with a portion extending over said rotary shaft and a portion extending beneath said rotary shaft; pivotal suspension and actuating means on the rotary shaft coordinated with the under-reaching portion of the feed bar to impart rise and fall movements to said bar; and means for imparting feed movements to the bar including a rocker, an oscillating shaft for said rocker, an eccentric on the rotary shaft, an associated strap with a vertical arm, a horizontal lazy bar fulcrumed at one end to swing on a fixed center and having pivotal connection at its other end with the vertical arm of the eccentric strap, an actuating arm with an arcuate slot having its center of curvature substantially coincident with said pivotal connection, and a link extending between said pivotal connection and another pivotal connection adjustable along the arcuate slot of the actuating arm for the purpose of varying the feed stroke of the feed bar.

4. Feed mechanism for sewing machines comprising a feed operating shaft; a feed bar pivotally supported at the front of the machine and extending inwardly over said shaft; feed lift means on said shaft in the vertical plane of said feed bar; and operating connections between said shaft and the pivotal support for the feed bar whereby feed and return movements are imparted to said bar.

5. Feed mechanism for sewing machines com prising a shaft; a feed bar with an arm extending forwardly toward the front of the machine over said shaft, and an arm extending forwardly beneath said shaft, both said arms lying in a single plane transversely of the machine; pivotal suspension and actuating means on the shaft coordinated with the front end of the underreaching arm of the feed bar to impart rise and fall movements to said bar; and means at the front of the machine coordinated with the front end of the over-reaching arm of the feed bar to impart feed movement to said bar.

6. Feed mechanism for sewing machines comprising a shaft; a feed bar with an arm extending said shaft, and an arm extending forwardly beneath said shaft, both said arms lying in a single plane transversely of the machine; pivotal suspension and actuating means for imparting rise and fall movements to the feed bar including an eccentric on said shaft, and an eccentric strap with a depending arm pivotally connected to the front end of the under-reaching arm of the feed bar; and means at the front of the machine coordinated with the front end of the over-reaching arm of the feed bar for imparting feed movements to said bar.

7. Feed mechanism for sewing machines comprising a shaft; a feed bar with an arm extending forwardly toward the front of the machine over said shaft and an arm extending forwardly beneath said shaft, both said arms lying in a single plane transversely of the machine; pivotal suspension and actuating means for imparting rise and fall movements to the feed bar including an eccentric on the shaft, and an eccentric strap with a depending arm pivotally connected to the front end of the under-reaching arm of the feed bar; and means at the front of the machine for imparting feed movements to the feed bar including a rocker pivotally connected with the front end of the over-reaching arm of the feed bar; and means on the shaft for oscillating the rocker.

8. Feed mechanism for sewing machines comprising a shaft; a feed bar with an arm extending forwardly toward the front end of the machine over said shaft; and an arm extending forwardly beneath said shaft, both said arms lying in a single plane transversely of the machine; pivotal suspension and actuating means on the shaft coordinated with the front end of the underreaching arm of the feed bar to impart rise and fall movements to said bar; and means at the front of the machine for imparting feed movements to the feed bar including a rocker having a pivotal connection with the front end of the over-reaching arm of the feed bar, an eccentric on the shaft, and an eccentric strap coordinated with said rocker.

GEORGE SAUER. 

